Lubricant



United States Patent 2,760,932 LUBRICANT Ellis K. Fields, Chicago, 111., and Roger W. Watson, Highland, Ind., assignors to Standard Oil Company, Chlcago, 111., a corporation of Indiana No Drawing. Application March 30, 1953, Serial No. 345,686

17 Claims. (Cl. 25232.7)

This invention relates to lubricating oil additives and to lubricants containing same. More particularly, it relates to novel phosphorus and sulfur containing bearing corrosion inhibitors prepared by reacting a phosphorus sulfide with a fraction of the oil phase of the liquid product resulting from the catalytic reaction of hydrogen and carbon monoxide at elevated temperatures and pressures. This oil phase or hydrocarbon stream, as it is often called, comprises predominantly hydrocarbons of varying molecular weight along with a relatively small proportion of oxygenated compounds.

Recent increased use of silver and copper in internal combustion engines, particularly in bearings, has created new problems in connection with the lubricants employed therewith. Present day lubricating oils contain numerous additives each with a particular purpose. Recently, it

has become apparent that certain additives either aloneor incombination, while effective to improve certain characteristics of the lubricant, adversely aifect other properties thereof. Many of the lubricant additives which are employed are sulfur-containing organic compounds which seem to increase corrosion of bearing surfaces containing silver or copper. Thus," for example, are employed such compounds as organic polysulfides, metal salts of organo-substituted thio acids of phosphorus, metal salts of the reaction product of a phosphorus sulfide with a hydrocarbon such as for example, polybutenes and other polyolefins, and combinations of the foregoing. While the corrosion incurred by the use of such additives can be substantially eliminated by avoiding their use, such a solution to the problem is accompanied by the loss of highly desired beneficial effects of such additives.

It is an object of the present invention to provide corrosion inhibitors for lubricating oils which are particularly suitable for use in conjunction with various sulfur-containing additives and particularly detergent additives. More particularly, it is an object to provide bearingcorrosion inhibitors which are exceptionally compatible with detergent additives of the neutralized phosphorus sulfideorganic compound reaction product type and which will substantially prevent corrosion of bearings comprising silver. or copper when oils containing such detergent addi: tives'are employed. Corrosion of bearings and other parts of internal combustion engines may, of course, occur for reasons other than the use of sulfur-containing additives such as detergent additives and it is, therefore, an object of the present invention to provide inhibitors suit: able, in general, for addition to lubricatingroils which will effectively prevent corrosion of bearings and otherlubrioated parts. Theseand additional objectsand advantages will be apparent from the following detailed description of the invention.

It is our discovery that surprisingly effective lubricant additives capable of inhibiting corrosion of bearings in internal combustion engines may be prepared by reacting a phosphorus sulfide, e. g. P253, P285, P483, P118791 other phosphorus sulfide, preferably P255, with a fraction of the oilphase of the liquid product resulting from the catalytic reaction of carbon monoxide and hydrogen at elevated temperatures and pressures. Such afraction con-' 2,760,932 Patented Aug. 28, 1956 tains from about 60 to about 90% hydrocarbons with the remainder consisting essentially of oxygenated compounds of various types, e. g. carboxylic acids, hydroxyl compounds, carbonyl compounds, etc. The process by which such high boiling fractions are produced will be referred to generally herein as a hydrocarbon synthesis process or simply as an HCS process and liquid fractions produced therein may be referred to as HCS fractions. The HCS process, which is hereinafter described in further detail, is essentially based upon the so-called Fischer-Tropsch process of well known German origin. In such processes carbon monoxide and hydrogen are catalytically reacted at elevated temperatures and pressuresto produce large quantities of hydrocarbons of varying molecular Weights and relatively smaller quantities of oxygenated compounds generally corresponding in molecular weight to such hydrocarbons. A catalyst comprising a metal or oxide thereof chosen from group VIII of the periodic table and particularly alkali metal-promoted iron, is ordinarily employed.

The total liquid product from the HCS reaction comprises a wide molecular weight range of organic The water .stream comprises oxygenated compounds of relatively low molecular weight, i; e. mostly hydroxyl,

. carboxyl, and. carbonyl compounds, containing from genated compounds of the same types but of higher 1 to about 5 carbon atoms. The separated hydrocarbon stream. contains a substantial amount ofzoxymolecular weights. It is, of course, usually desirable to separate the oxygenated compounds from the oil so that they may be refined and individually recovered while the oil is then refined and fractionated into cuts corresponding essentially to those obtainable from petroleum, e. g. gasoline, heater oil, kerosene, etc. A method of processing the oil stream to attain such separations and recoveries is described in U. S. 2,625,560 to V. F. Michael. As a practical matter, however, the higher molecular weight oxygenated compounds in the hydrocarbon stream are so organophilic that complete separation is usually impossible. For this reason, the hydrocarbon stream has been contacted with bauxite or the like at elevated temperatures to convert the oxygenated compounds to hydrocarbons, usually olefins, before employing the same as motor fuel, etc. i

In accordance with the present invention, no attempt is made to recover the high molecular weight oxygenated compounds from the hydrocarbon stream; after lowmolecular weight oxygenated compounds are scrubbed out of the hydrocarbon stream it is fractionated into relatively narrow, high boiling cuts, each of which contains both hydrocarbons and oxygenated compounds in substantially the proportions found in the total hydrocarbon stream. HCS fractions employed, in accordance herewith, are

preferably those relatively narrow fractions which have a product which is substantially free of water and preferentially water soluble materials.

The addition of from about 0.01% to about 10% and preferably from about 0.02% to about 3% of the product resulting from the reaction of a phosphorus sulfide with a hydrocarbon-and-oxygenated-compound-containing fracu tion of the type described will, when added to a lubricating oil, impart outstanding corrosion protection, particularly with respect to silver and copper-lead bearings and the like. The method by which the phosphorus sulfide and hydrocarbon-oxygenated fractions are reacted to produce the additive will be hereinafter set forth in detail.

The above-described reaction products are exceptional in their ability to inhibit corrosion of copper-lead bear ings but somewhat less effective for silver bearings, It has been found, however, that treatment of the HCS oil product with aqueous caustic prior to reacting the same with a phosphorus sulfide results in a finished additive having substantially improved ability to inhibit corrosion of both copper-lead and silver bearings. Such treatment apparently converts carboxylic acids tosoaps' which are water-soluble and readily separated and serves to. improve the corrosion inhibition properties of additives of the present invention.

The, hydrocarbon oxygenated compound containing fractions (HCS oil products) preferably employed in accordance herewith are those prepared by the reduction of carbon monoxide over an alkali metal promoted iron catalyst in accordance with a process of the type described in U. S. 2,527,846 granted to I. A. Phinney et al. In a process of that type, which in itself does not constitute a part of the present invention, carbon monoxide and hydrogen are reacted in ratios of between about 2:1 and 1:3 and usually at temperatures between about 200 and 700 F. and at pressures from about 1 to- 40 atmos pheres in the presence of a fluidized catalyst comprising iron oxide promoted by an alkali metal such aspotassiurn. Further. description, of the HCS reaction is set forth in each of the above-mentioned patents and further discussion'herein is, therefore, considered unnecessary. Whereasparticular reference is made to an iron or iron oxide. catalyst for use in the reaction of carbon monoxide and hydrogen, it is recognized that carbon monoxide reductionprocesses of this type can be carried out with catalysts comprising in addition to iron, various other metals and that on the-other hand such may be carried out with other catalysts, particularly those of the eighth group of theperiodic table. Variation of catalyst and operating conditions can substantially affect product distribution, =but solong as. the resulting product is a hydrocarbon oxygenated compound fraction comprising those constituents in the amounts specified, suchfraction may be employed for purposes of the present invention.

Itis preferred in accordance herewith to employ HCS oil products of narrow boiling range. More specifically, the fraction employed should have a boiling range substantially corresponding to the boiling-point of an individual normalparafiin in the range offrom about heptane to about eicosane and preferably from about decane to about 'octadecane without any substantial amount, i. e. no more than about of the fraction boiling above orbelow that point.

A typical C10 cut of the HCS oil product freed of all water solubles' and having no more than about 10% of thefraction boiling on either side of n-decane (345 F.) has a composition approximately as follows:

20% normall-olefins. 121% other normal olefins 11% I tertiary olefins 13% other branchedolefins- 7%v normal parafilns- 8% branched paraffins 9% a omat cs c rb xylic acids tbonyl compounds 6% hydroxyl compounds 6%. her Oxygen compo n s The hydroxyl compounds in each boiling range areapuroximately twocarbonatoms less than the other compounds; 't-hus, fiese cputalna ou eight carb n atom tead often as: do

e res The above composition is more or less typical for the fractions throughout the disclosed range. In general, however, for purposes of the present invention, those HCS oil products containing from about 60 to about 85% hydrocarbons and from about 15 to about 40% oxygenated compounds and preferably from about 70% to about hydrocarbons and about 20% to about 30%- oxygenated compounds, wherein the oxygenated compounds comprise carboxyl, hydroxyl and carbonyl compounds, may be employed for purposes of this invention. While it is preferred to employ narrow cuts, e. g. C10, such is not necessary and considerably wider cuts may be used which, contain a variety of molecular weight hydrocarbons and oxygenated compounds.

The reaction of a phosphorus sulfide, with such a fraction maybe carried out at a temperature from about 200 F. to about 450 F. and preferably from 300 F. to about 400 F. It is advantageous to maintain a, non-oxidizing, atmosphere, such as, for, example, an atmosphere of. mi trogen above the reaction mixture. From about 1% to about 50% and preferably from about 5% to 25%, by weight, of P255 or other phosphorus sulfide based upon total reactants may be used. Usually, it is preferable to use an amout of P285 that will completely react with the organic fraction. However, excess Pass may be used. and separated from the product after the heating is discontinned. by filtering or diluting with a solvent such as hexane, filtering and distilling off the solvent. The re action product may be further treated by blowing with nitrogen at an elevated temperature of from about 200 F. to about 600 F. to improve the odor there-of.

. It has been found that the effectiveness of lubricant additives prepared in accordance herewith is considerably improved when the hydrocarbon-oxygenated-compoundcontaining fraction is treated with aqueous caustic, or the. like, prior to reacting the same with a phosphorus sulfide. It is preferred to employ an aqueous solution of sodium hydroxide. Such caustic solution should com prise about 2 to about 20% caustic and preferably from about, 6 tov about 12%. Potassium hydroxide may, of course, be employed if desired.

The ability of the additives of the present invention to inhibit corrosion of silver and copper-lead bearings is demonstrated by data hereinafter set forth in Example l and Table 1. These data were obtained by subjecting mixtures of. a.- mineral lubricating oil, a neutralized re. action product of P285 and a polybutylene, and various phosphorus. sulfide-HOS oil stream reaction products to he. test (a corrosion test of the Electromotive Di: vision; of General Motorsv Corporation) and. the SSCT test, (stirring sand. corrosion test).

In the. EMD test a silver strip 2 cm. x 5.5; cm. with a small hole at one end for suspension is lightly abraded with No. 0 steel wool, wiped free of any adhering. steel wool, washed with carbon tetrachloride, air-dried and then weighed to 0.1 milligram. Three hundred cc. of the oil to be tested is placed in a 500 cc. lipless glass beaker and the oil is heated to a. temperature of 300 F. (:2 F.) and the silver test strip suspended in the oil so that the stripis completely immersed therein. The oil in the beaker is stirred by means of a glass, stirrer operating at 300R. P. M. At the end of twenty-four hours, the silver strip is removed, and while still hot rinsed thoroughly with carbon tetrachloride and airadried. The appearance of the strip is then visually noted and given ratings accord= ing to the following scale:

1 Brig ht 2.Stained 3.Grey-black 4- Black, smooth 5.-Bla.ck, flake After the visual inspection the silver strip is immersed in a- 10 potassium cyanide solution at room temperature until the silver surface assumes its original bright or silver appearance. The silver strip is then washed successively with .distilled water and acetone, air-dried, and weighed. A weight loss of 20 mg. or less is considered passing.

The SSCT test is conducted as follows: A copper-lead test specimen is lightly abraded with steel wool, washed with naphtha, dried and weighed to the nearest milligram. The cleaned copper-lead test specimen is suspended in a steel beaker, cleaned with a hot tri-sodium phosphate solution, rinsed with Water, acetone and dried, and 250 grams of the oil to be tested, together with 0.625 gram lead oxide, and 50 grams of a 30-35 mesh sand charged to the beaker. The beaker is then placed in a bath or heating block and heated to a temperature of 300 F. (i2 F.) while the contents are stirred by means of a stirrer rotating at 750 R. P. M. The contents of the beaker are maintained at this temperature for twenty-four hours, after which the copper-lead test specimen is removed, rinsed with naphtha, dried and weighed. The test specimen is then replaced in the beaker and an additional 0.375 gram of lead oxide added to the test oil. At the end of an additional twenty-four hours oftest operation the test specimen is again removed, rinsed and dried as before, and weighed. The test specimen is again placed in the beaker together with, an additional 0.250

gram of lead oxide and the test continued for another twenty-four hours (seventy-two hours total). At the conclusion of this time, the test specimen is removed from the beaker, rinsed in naphtha, dried and weighed. The loss in weight of the test specimen is recorded after each weighing. A weight loss of 200 mg. or less in 48 hours and 500 mg. or less in 72 hours is allowable.

For purposes of illustrating the method whereby the additives of the present invention may be prepared, the following examples are provided:

EXAMPLE 1 A mixture of 180 cc. of a relatively wide boiling fraction of total HCS-oil product (freed of all water and water solubles) prepared substantially as described in U. S. 2,527,846 and having a boiling range of from 280 F. to 410 F., and 66 grams of P285 were stirred together at 300 to 320 F. for 2 hours, cooled, and filtered to obtain 192 grams of a dark brown, clear liquid. This liquid was soluble in mineral oil and evolved substantially no HzS. This liquid in an amount of 0.75% was added to an SAE30 base mineral lubricating oil which contained 3.3% of a phosphorus, sulfur, and barium containing detergent additive resulting from the barium hydroxide neutralization of the reaction product of P235 and polybutylene polymer. The lubricant thus prepared was tested in the SSCT test and gave 32 mg, 48 mg. and 78 mg. losses in 24, 48 and 72 hours respectively. Obviously, these results are exceptional.

EXAMPLE 2 A mixture of 140 grams of an alkali washed C fraction which had essentially the composition set forth hereinabove, and 44 grams of P255 Was stirred at 300 to 325 F. under a nitrogen blanket for 3 hours. The product was cooled and filtered to obtain 167 grams of a light brown mobile oil, containing 5.04% phosphorus and 12.85% sulfur, which was oil soluble.

EXAMPLE 3 A mixture of 140 grams of the same alkali washed C10 fraction employed in Example 2 and 66 grams of P285 was stirred at 300 to 325 F. under a nitrogen blanket for two hours. The product was cooled and filtered to obtain 194 grams of a light brown mobile oil, containing 6.72% phosphorus and 16.74% sulfur, which was oil soluble.

EXAMPLE 4 A mixture of 140 grams of the alkali washed C10 fraction of Example 2 and 88 grams of P255 was stirred at Table sso'r (wt. loss in EMD (wt. mg.)

Product Fromloss in 48 Hrs. 72 Hrs.

Ex. 2 1 20 3 330 1 8/1 60 100 t 5/1 95 1 Appearance rating.

A further test employing the product of Example 2, wherein a 1% concentration of that material in combination with 3.3% of the detergent additive referred to in Example 1 was added to an SAE30 base oil, was conducted in the- L-4 engine test. connecting rod bearings in this test, which is described on page 67 of Motor Oils and EngineLubrication, by Georgi (Rheinholdl950), were 0.14 gram, 0.17 gram and 0.22 gram and the bearings were smooth, blue-black in appearance.

In addition to the aforementioned detergent-type additives and corrosion inhibitors, compositions containing the herein-described products of phosphorus sulfide-HCS oil stream reaction can contain other additives, such as anti-oxidants, pour-point depressors, extreme pressure agents, antiwear agents, V. I. improvers, etc.

While this invention has been described in connection with the use of the herein-described additives in lubri cant compositions, their use is not limited thereto; but the same can be used in products other than lubricating oils, such as for example, fuel oils, insulating oils, greases, non-drying animal and vegetable oils, waxes, asphalts, and any fuels for internal combustion engines, particul'arly where sulfur corrosion must be combatted.

Concentrates of a suitable oil base containing more than 10% of the herein-described phosphorus sulfide- HCS oil stream reaction products alone or in combination with more than 10% of the detergent-type additive and/ or the herein-described compounds normally corrosive to silver, can be used for blending with hydrocarbon oils or other oils in the proportions desired for the particular conditions of use to give a finished product containing from 0.01% to 10% of the phosphorus sulfide- HCS oil stream reaction product alone or in combination with from 0.001% to about 10% of the detergent-type additive and/or the compound normally corrosive to silver.

Percentages given herein and in the appended claims are weight percentages unless otherwise stated.

Although the present invention has been described with reference to specific preferred embodiments thereof, the invention is not to be considered as limited thereto but includes within its scope such modifications and variations as come within the spirit of the appended claims.

What we claim as novel and desire to protect by Letters Patent is as follows:

1. A composition comprising the substantially olefinfree reaction product obtained by reacting at a temperature in the range of from about 200 F. to about 450 F. -a phosphorus sulfide with a fraction boiling in the range of from about 200 F. to about 650 F. of the hydrocar- 'bon phase of the liquid product resulting from the catalytic reduction of carbon monoxide with hydrogen at elevated temperatures and pressures, said fraction com prising at least about 60% hydrocarbons and a substantial amount of oxygenated compounds.

The weight losses of the 2. The composition of claim 1 wherein the oxygenated compounds in said fraction comprise a mixture of carboxyl, hydroxyl, and carbonyl compounds.

3. The composition of claim 1 wherein the phosphorus sulfide is P255. 1 4. A composition comprising the substantially olefinfree reaction product obtained by reacting at a temperature in the rangeof from about 200 F. to about 450 F., a phosphorus sulfide with a narrow boiling fraction of the hydrocarbon phase of the liquid product resulting from a catalytic reduction of carbon monoxide with hydrogen at elevated temperatures and pressures which substantially corresponds in boiling range to an individual normal parafiinic hydrocarbon in the range of from about heptane to about eicosane, said fraction comprising about 60% to about 90% hydrocarbons and the remainder oxygenated compounds.

5. A lubricant comprising a mineral lubricating oil and from about 0.001% to about by weight of the composition of claim 1.

6. A lubricant comprising a mineral lubricating oil, from about 0.001 to about 10% by weight of a neutralized product of the reaction of a phosphorus sulfide and a butylene polymer and from about 0.01 to about 10% by weight of the composition of claim 1.

7. A lubricant comprising a mineral lubricating oil containing from about 0.001 to about 10% by weight of the neutralized reaction product of a phosphorus sulfide and a butylene polymer and from about 0.01 to about 110% by weight of the composition of claim 3.

8. A composition comprising substantially olefin-free reaction product of a phosphorus sulfide with an alkali washed fraction boiling in the range of from about 200 F. to about 650 F. of the hydrocarbon phase of the liquid product resulting from the catalytic reduction of carbon monoxide with hydrogen at elevated temperatures and pressures, said alkali washed fraction comprising about 60% to about 90% hydrocarbon and the remainder oxygenated compounds.

9. The composition of claim 8 wherein the oxygenated compounds in said fraction comprise a mixture of hydroxyl and carbonyl compounds.

10. The composition of claim 8 wherein the phosphorus sulfide is P285.

'11.- A composition comprising the substantially olefinfree reaction product obtained by reacting at a temperature in the rangeof from about 200 F. to about 450 F., a phosphorus sulfide with an alkali washed narrow boiling fraction of the hydrocarbon phase of the liquid product resulting from a catalytic reduction of carbon monoxide with hydrogen at elevated temperatures and pressures which substantially corresponds in boiling range to an individual normal paraflinic hydrocarbon in the range of from about hepta-ne to about eicosane, said alkali washed fraction comprising about to about hydrocarbons and the remainder oxygenated compounds.

12'. A lubricant comprising a mineral lubricating oil and from about 0.01% to about 10% by weight of the composition of claim 8.

13. A lubricant comprising a mineral lubricating oil, from about 0.001% to about 10% by weight of a neutralized product of the reaction or" a phosphorus sulfide and a butylene polymer and from about 0.01% to about 10% by weight of the composition of claim 8.

14. A lubricant comprising a mineral lubricating oil containing from about 0.001% to about 10% by weight of the neutralized reaction product of a phosphorus sulzfide and a butylene polymer and from about 0.01 to about 10% by weight of the composition of claim 10.

15. A lubricant comprising a mineral lubricating oil and from about 0.01% to about 10% by weight of the composition of claim 4.

16. A concentrated solution in hydrocarbon oil of the composition of claim 1 which solution is capable of dilution with a mineral lubricating oil to form a homogeneous mixture containing from about 0.01% to about 10% of said composition.

17. A concentrated solution in hydrocarbon oil of the composition of claim 8 and the neutralized reaction product of a phosphorus sulfide and a butylene polymer which solution is capable of dilution with a mineral lubricating oil to form a homogeneous mixture containing from about 0.01% to about 10% of the composition of claim 8 and from about 0.001% to about 10% by weight of the neutralized reaction product of a phosphorus sultide and a butylene polymer.

References Cited in the file of this patent UNITED STATES PATENTS 2,570,032 Heinrich Oct. 2, 1951 

1. A COMPOSITION COMPRISING THE SUBSTANTIALLY OLEFINFREE REACTION PRODUCT OBTAINED BY REACTING AT A TEMPERATURE IN THE RANGE OF FROM ABOUT 200*F. TO ABOUT 450* F. A PHOSPHORUS SULFIDE WITH A FRACTION BOILING IN THE RANGE OF FROM ABOUT 200* F. TO ABOUT 650* F. OF THE HYDROCARBON PHASE OF THE LIQUID PRODUCT RESULTING FROM THE CATALYTIC REDUCTION OF CARBON MONOXIDE WIT HYDROGEN AT ELEVATED TEMPERATURES AND PRESSURES, SAID FRACTION COMPRISING AT LEAST ABOUT 60% HYDROCARBONS AND A SUBSTANTIAL AMOUNT OF OXYGENATED COMPOUNDS.
 6. BON PHASE OF THE LIQUID PRODUCT RESULTING FROM THE CATAFROM ABOUT 0.001 TO ABOUT 10% BY WEIGHT OF A NEUTRALIZED PRODUCT OF THE REACTION OF A PHOSPHORUS SULFIDE AND A BUTYLENE POLYMER AND FROM ABOUT 0.01 TO ABOUT 10% BY WEIGHT OF THE COMPOSITION OF CLAIM
 1. 